JP3248803B2 - Al alloy plate for full open end with excellent openability and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end material for a food can, excluding a beverage can, and more particularly, to a ring pull (RP) attached to a can lid without requiring a can opener for opening the can. )
The present invention relates to an Al alloy plate for a full open end (hereinafter referred to as FOE) in which a can lid is opened on the entire surface by pulling up a tab and a method for manufacturing the same.

[0002]

BACKGROUND OF THE INVENTION Food cans are defined as tin, aluminum, tin-free steel (T
FS) and other containers made of thin plates.
It is sealed and heat-sterilized, or aseptically filled and sealed with pre-heat-sterilized food to make a can.

[0003] Until now, the lid of a food can required a can opener to open the can, which was very troublesome. However, in recent years, it has become unnecessary to open the can, and by raising the RP tab attached to the can lid. The FOE in which the can lid portion is opened on the entire surface has become widespread.

[0004] Aluminum materials and tinplates are used for FOE, but aluminum is becoming popular from the viewpoint of openability. However, since the FOE has a large opening, the can opening load is higher than the partial open end used for beverage cans and the like, and it is necessary to reduce the can opening load.

[0005] In the FOE, a wedge-shaped press-in process called a score is applied to the opening after coating so that the can can be easily opened. Although it is possible to achieve this, a coating defect on the inner surface of the can lid increases, and depending on the contents, corrosion may occur from the coating defect.

In addition, when a heat treatment is performed after scoring due to repair or retort in order to repair coating film defects, the can opening load tends to increase and the opening property tends to decrease.

Conventionally, AA has been used as a FOE material for food cans.
After hot-rolling an Al alloy ingot having a component such as 5052, a material that has been cold-rolled at a relatively high rolling rate is used. However, when the AA5052 alloy is used, the score tear at the time of opening the can is used. Since the load was high and the progress of tearing was poor, cracks were generated in places other than the score, and the entire mouth of the drinking mouth was sometimes not opened. Further, although the tear load is reduced by increasing the strength, it is necessary to further perform high cold rolling in order to improve the strength with the AA5052. However, when the high cold rolling is performed, the crystal grains become flat. There has been a problem that the grains become elongated grains and the rivet workability for mounting the RP tab, which is one of the important characteristics of the FOE, is reduced.

[0008] In contrast, AA5182 alloy, which is often used for the partial end of beer, carbonated beverages, etc., has high strength and can obtain sufficient strength to reduce the tear load when opening cans. However, 3P (piece) cans using tin are often used for food cans,
Since the shock absorption of the body is inferior, cracks may occur in the score portion. Therefore, a significant increase in strength is disadvantageous for maintaining the shock absorbing properties of the end itself.

A production method proposed in Japanese Patent Application Laid-Open No. 63-286546 is a method for producing a can-end material such as a beverage can. Although the strength is adjusted by finish annealing at a temperature of 250 ° C., the material subjected to finish annealing increases the amount of deformation at the time of can opening and increases the can opening load.

Therefore, the conventional materials and manufacturing methods cannot satisfy the characteristics required as the FOE end material for food cans, and a material having a sufficient tearing property is required to improve the openability of the can. It becomes necessary.

The present invention has been made in order to solve the above-mentioned problems of the prior art and to meet the above-mentioned demand, and provides an Al alloy plate for food cans FOE excellent in can openability and a method for producing the same. The purpose is to do so.

[0012]

Means for Solving the Problems As means for solving the above problems, the present invention provides:
Mn: 0.30 to 0.60%, Fe: 0.10 to 0.30% as essential components, and Si ≦ 0.30 if necessary.
%, Ti ≦ 0.20%, and Cu ≦ 0.20%, and the balance has a chemical component consisting of Al and unavoidable impurities. 20 μm Al
The Fe-Mn intermetallic compound has an area occupancy of 0.3 to 1.0.
% Of an Al alloy plate for a full open end of a food can with excellent openability.

In another aspect of the present invention, an Al alloy ingot having the above-mentioned chemical composition is soaked at 470 to 530 ° C., then hot-rolled, and further cold-rolled by 30% or more. , An intermediate alloy in the range of 360 to 540 ° C, and then cold rolling at a rolling rate of 30 to 80% to obtain an Al alloy sheet. The gist is a method of manufacturing an Al alloy plate for a can full open end. The present invention
In the method (1), after the cold rolling, the finish annealing is not performed. Manufacture
Cold rolled aluminum alloy plate for full open end
It is an Al alloy plate as it is.

[0014]

The present invention will be described below in more detail. First, the results of the study that led to the finding of the present invention will be described.

In order to achieve the above object, the present inventors have:
Focusing on the improvement of openability when increasing the amount of intermetallic compounds using existing materials, Al for food cans FOE with excellent openability
We worked diligently to develop alloy materials.

First, the present inventors have investigated the relationship between the intermetallic compound and the openability.
It was found that the tear load at the time of opening the can was reduced. That the increase in intermetallic compounds contributes to the improvement of tearability,
"Reports of the 74th Spring Meeting of the Japan Institute of Light Metals", p.
92, this technique uses 300
When a score is given to a 4 alloy plate, it is shown that a large increase in the amount of Fe added is necessary to reduce the tear load.

However, in consideration of the corrosion resistance and moldability of the food can FOE to which the present invention is applied, the upper limit of the amount of Fe added is 0.3%. It was determined that it was impossible.

Therefore, when the Fe and Mn contents and the production conditions were adjusted to change the intermetallic compound diameter, it was found that the tearability could be improved with a relatively small amount of Fe added.

The effect is remarkably observed at 3 μm or more in the Al—Fe—Mn intermetallic compound, and it is found that the larger the intermetallic compound having a relatively large intermetallic compound diameter is better at the same area ratio. did. However, it has been found that the coarsening of the intermetallic compound causes a decrease in rivet formability, which is an important characteristic of the FOE, and therefore, it is necessary to control the size to 20 μm or less.

Further, the strength range of the FOE (proof strength: 215 to 2
At 75 N / mm ² ), it was found that a relatively high strength was excellent in can openability, and further that a stabilization annealing after finish cold rolling was not performed was excellent in tearability and improved can openability. .

Accordingly, it has been found that a material for a food can FOE having relatively high strength and excellent openability can be obtained without stabilized annealing by appropriately controlling the rolling reduction after the intermediate annealing. .

The present invention makes it possible to achieve the initial object by adjusting the chemical components and regulating the conditions of the soaking and the cold rolling process (including the intermediate annealing) based on such knowledge. It was done.

Next, the reasons for limiting the chemical components of the Al alloy in the present invention will be described.

Mg: Mg is an important element for imparting strength, and is an essential component in the present invention. Unless added at least 1.70% or more as a food can FOE material, sufficient strength cannot be obtained. However, if added excessively, the strength may be too high and the score may crack due to the impact at the time of dropping, and the moldability may be reduced. Therefore, the upper limit of the added amount is 2.70%. Therefore, the amount of Mg to be added is in the range of 1.70 to 2.70%.

Mn: The addition of Mn has a great effect on the formation of Al-Fe-Mn-based intermetallic compound which improves the tearing property which contributes to the improvement of the can openability and the strength is improved. Mn is also an essential component in the present invention. Things. At least 0.30% or more must be added in order for the effect of improving tearing properties to appear. However, if added excessively, the number of fine intermetallic compounds generated becomes too large, which leads to a decrease in moldability and does not contribute to an improvement in can openability. Therefore,
The addition amount of Mn is 0.30 to 0.60%.

Fe: Addition of Fe improves Al opening ability.
This is effective in producing a -Fe-Mn-based intermetallic compound. Also,
It has a great effect on the refinement of crystal grains to improve the formability, which is a property required as an end material, and the more the amount of the additive, the more refined. However, if the content is less than 0.10%, the effect is not recognized.
In addition to reducing the corrosion resistance, which is an important characteristic of the OE, the generation of giant intermetallic compounds and the number of crystallized substances are excessively increased, resulting in deterioration of the moldability. Therefore, the amount of Fe added is 0.10 to 0.30%.

Intermetallic compound: By adding Fe and Mn, (F
e, although the intermetallic compound such as Mn) Al ₆ is generated, and an intermetallic compound more than 3μm is to contribute to the improvement of the can opening property, it is necessary to adjust the production conditions. However, the formation of a huge intermetallic compound causes a reduction in moldability.
It is necessary to control to less than μm. When viewed from the product plate surface, the area occupancy of these intermetallic compounds is 0.3 to
It is preferably 1.0%. This is because if less than 0.3%, the effect of tearing property is not recognized, and if it exceeds 1.0%, the moldability is significantly reduced.

In the present invention, the above Mg, Mn and Fe are used.
Is an essential component, but one or more of the following elements can be contained in an appropriate amount as needed.

Si: The addition of Si has an effect on the formation of an Mg-Si based intermetallic compound which improves the tearability. But,
If it is added excessively, the number of intermetallic compounds generated becomes too large and the formability is significantly reduced.
30% or less.

Ti: Ti is an effective element for stabilizing the structure, but when added in a large amount, Ti forms a large intermetallic compound to lower the formability. Therefore, Ti
Is 0.20% or less.

Cu: The addition of Cu is effective in improving the strength.
However, when added in excessive amounts, the corrosion resistance, which is an important property as an end, is reduced, and the work hardening is increased, so that the strength becomes too high and the moldability is reduced. Therefore,
The added amount of Cu is 0.20% or less.

Next, the manufacturing process of the present invention will be described.

The Al alloy having the above-mentioned chemical components is melted and cast by a conventional method. Homogenizing heat treatment of the obtained ingot is performed by the Al-Fe-Mn intermetallic compound found on the surface of the product plate. It is carried out at a condition of 3 to 20 μm, that is, at 470 to 530 ° C. If the temperature of the homogenization heat treatment is lower than 470 ° C., the intermetallic compound cannot grow sufficiently, resulting in a decrease in the openability of the can. It is not preferable because the amount is too large and the moldability is remarkably reduced.

After the homogenizing heat treatment, hot rolling and cold rolling are performed. In the present invention, as shown below, a cold rolling step including an intermediate annealing under a predetermined condition is carried out to improve the openability of the can. It is characterized by setting an effective intensity level for improvement.

First, the cold rolling reduction before the intermediate annealing is 30%.
If it is less than 30%, the crystal grains after the intermediate annealing become large, which adversely affects the formability, which is a necessary property of the end, so that the content is required to be 30% or more. Considering the moldability at the product thickness, it is preferably at least 60%.

Next, intermediate annealing is performed, and the temperature of the intermediate annealing is in the range of 360 to 540 ° C. The reason is 360
If the temperature is lower than ℃, unrecrystallization is caused, leading to a decrease in formability. On the other hand, if the temperature is higher than 540 ° C., the crystal grains become coarse and the formability is also lowered.

[0037] Cold rolling after intermediate annealing is a condition that greatly affects the strength. If the rolling reduction is less than 30%, the required strength cannot be obtained. Although an increase in the rolling ratio is effective for improving the strength, when the rolling ratio exceeds 80%, the anisotropy of the material increases, and the anisotropy of the can opening load depends on the processing direction of the opening with respect to the rolling direction of the material. Occurs. Further, since the reduction in formability is remarkable, the cold rolling reduction after the intermediate annealing is 30 to 80.
% Range.

The strength is adjusted by the above manufacturing steps and conditions. The reason why the finish annealing is not performed is that when the same strength is adjusted by the finish annealing, the formability is improved,
This is because the amount of deformation at the time of opening the can is increased and the opening load is increased.

Next, examples of the present invention will be described.

[0040]

Example 1 An ingot of an Al alloy having the chemical components shown in Table 1 was held at a temperature of 510 ° C. for 4 hours as a homogenizing heat treatment, and thereafter, the sheet thickness was adjusted to 2.0 mm by hot rolling. Next, after each sample was subjected to cold rolling to a sheet thickness of 0.75 mm, the sheet thickness was subjected to a heat treatment at a temperature of 420 ° C. and a holding time of 0 second in a continuous heating and annealing furnace, and the sheet was further subjected to cold rolling. The thickness was 0.25 mm. About this cold rolled sheet,
Since the end material is molded after painting, 200 ° C x 20
Baking treatment was performed for the same conditions as in the case of coating. Table 2 shows the material properties (mechanical properties, tear load, rivet extension properties) of the test material having a product plate thickness of 0.25 mm after the baking treatment.

The tear test method is as shown in FIG. First, a score of "C" is formed on a 40 × 40 mm plate. The remaining thickness after scoring is a general FOE (140
１５０150 μm). After that, fix the board,
It was pulled up in the same direction as the scored surface, and the maximum load at the time of tearing was measured.

As shown in FIG. 2, the rivet overhang test was carried out with a punch having a punch diameter of 6 mm and a ball tip having a tip of 3R.
An overhang was performed on a × 25 mm plate with a constant wrinkle pressing force, and the overhang height was changed to determine the critical height.

From Table 2, the following is considered. No. 1 to No. 3 of the present invention have a low can opening load and are excellent in can opening properties. The rivet overhanging formability, which is a necessary property of the FOE material, is also sufficiently provided.

On the other hand, in the comparative examples No. 4, No. 6, No. 8,
No. 10, No. 12, and No. 13 do not have the intermetallic compound area occupancy or sufficient strength to improve the openability, and therefore, a decrease in the tear load is observed. Also,
No. 5, No. 7, No. 9, No. 10, No. 1 of Comparative Examples
In No. 12, the intermetallic compound was excessively increased or the strength was too high, so that the deterioration of the moldability was recognized.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

Example 2 A plate was manufactured from an Al alloy ingot having the same chemical composition as No. 2 in Table 1 under the manufacturing conditions shown in Table 3, and the proof stress, the tear load, and the rivet extension limit height were examined.
The results are also shown in Table 3.

As is clear from Table 3, No. 14 to No. 18 of the Al alloy plate obtained by the production method of the present invention are as follows.
It can be seen that all show good tearability and moldability.

On the other hand, the comparative examples No. 19 to No. 2
No. 6 is out of production conditions, and therefore has insufficient strength.
Due to excessive strength, the tear load increases and the formability decreases. Comparative Example No. 26 was subjected to finish annealing after cold rolling and adjusted to the same yield strength as Example No. 16 of the present invention. However, although the formability was improved, the can opening load was increased. You can see that there is. This is because the elongation increased by the finish annealing promoted deformation near the broken portion when the score was broken when the can was opened, and the load required for the deformation increased.

[0050]

[Table 3]

[0051]

As described in detail above, according to the present invention,
In the food can FOE material, a load at the time of opening the can after retort and repair is relatively low, so that a material that sufficiently satisfies the end characteristics can be obtained, and it is possible to sufficiently cope with thinning and high strength. It is also excellent in terms of manufacturing (stability, cost).

[Brief description of the drawings]

FIG. 1 is a view for explaining a can opening test method.

FIG. 2 is a diagram illustrating a rivet overhang test method.

Claims (3)

(57) [Claims] 1. Mg in weight percent (the same applies hereinafter): 1.70
To 2.70%, Mn: 0.30 to 0.60%, Fe:
0.10 to 0.30% as an essential component, the balance being A
1 and a chemical component consisting of unavoidable impurities, and that when viewed from the surface of the product plate, the Al-Fe-Mn intermetallic compound of 3 to 20 µm has an area occupancy of 0.3 to 1.0%. Food can full open end A with excellent openability
1 alloy plate. 2. The method according to claim 1, further comprising: Si ≦ 0.30%, Ti ≦ 0.2
0%, Al alloy plate according to claim 1, characterized in that it contains a Cu ≦ 0.20% either one or two or more. 3. An Al alloy ingot having the chemical component according to claim 1 or 2 is subjected to a soaking treatment at 470 to 530 ° C., then subjected to hot rolling, and further subjected to cold rolling of 30% or more. , An intermediate alloy in the range of 360 to 540 ° C, and then cold rolling at a rolling rate of 30 to 80% to obtain an Al alloy sheet. Manufacturing method of Al alloy plate for can full open end.